South Atlantic overturning and heat transport variations in ocean reanalyses and observation-based estimates

Autor(en)

Jonathan Andrew Baker, Richard Renshaw, Laura Claire Jackson, Clotilde Dubois, Doroteaciro Iovino , Hao Zuo, Renellys C. Perez, Shenfu Dong, Marion Kersalé, Michael Mayer, Johannes Mayer, Sabrina Speich, Tarron Lamont

Abstrakt

The variability in the South Atlantic Meridional Overturning Circulation (MOC) and meridional heat transport measured across 34.5∘ S during 2013–2017 differs significantly between observational and ocean reanalysis estimates. Variability in an ocean reanalysis ensemble and an eddy-resolving reanalysis is similar to an altimeter-based estimate but smaller than energy-budget and mooring-based estimates. Over 1993–2020, there is no long-term trend in the ensemble-mean overturning and heat transport, although there are inter-model differences, whereas the altimeter-based and energy-budget estimate transports increase over this period. Time-mean overturning volume transport (and the depth of maximum overturning) across 34.5∘ S in the ensemble and observations are similar, whereas the corresponding mean heat transports differ by up to 0.3 PW. The seasonal cycle of these transports varies between estimates, due to differences in the methods for estimating the geostrophic flow and the sampling characteristics of the observational approaches. The baroclinic, barotropic, and Ekman MOC components tend to augment each other in mooring-based estimates, whereas in other estimates they tend to counteract each other, so the monthly-mean, interannual, and seasonal MOC anomalies have a greater magnitude in the mooring-based estimates. Thus, the mean and variation in real-world South Atlantic transports and the amplitude of their fluctuations are still uncertain. Ocean reanalyses are useful tools to identify and understand the source of these differences and the mechanisms that control volume and heat transport variability in the South Atlantic, a region critical for determining the global overturning pathways and inter-basin transports.

Organisation(en)

Institut für Meteorologie und Geophysik

Externe Organisation(en)

Met Office, Mercator Ocean International, National Oceanic and Atmospheric Administration, Direction générale de l'armement, University of Cape Town, Department of Environment, Forestry and Fisheries, Bayworld Centre For Research & Education, Euro-Mediterranean Centre for Climate Change (CMCC), European Centre for Medium-Range Weather Forecasts (ECMWF), École Normale Supérieure, Paris

Journal

State of the Planet

Band

1

DOI

https://doi.org/10.5194/sp-1-osr7-4-2023

Publikationsdatum

09-2023

Peer-reviewed

Ja

ÖFOS 2012

105206 Meteorologie

ASJC Scopus Sachgebiete

Atmospheric Science

Link zum Portal

https://ucris.univie.ac.at/portal/de/publications/south-atlantic-overturning-and-heat-transport-variations-in-ocean-reanalyses-and-observationbased-estimates(7a6dc42c-cfea-4d51-97e6-98271e535581).html